mirror of
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396 lines
11 KiB
C++
396 lines
11 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is mozilla.org code.
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*
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* The Initial Developer of the Original Code is
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 1998
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either of the GNU General Public License Version 2 or later (the "GPL"),
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* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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/*
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A stack-based lock object that makes using PRLock a bit more
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convenient. It acquires the monitor when constructed, and releases
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it when it goes out of scope.
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For example,
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class Foo {
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private:
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PRLock* mLock;
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public:
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Foo(void) {
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mLock = PR_NewLock();
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}
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~Foo(void) {
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PR_DestroyLock(mLock);
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}
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void ThreadSafeMethod(void) {
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// we're don't hold the lock yet...
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nsAutoLock lock(mLock);
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// ...but now we do.
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// we even can do wacky stuff like return from arbitrary places w/o
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// worrying about forgetting to release the lock
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if (some_weird_condition)
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return;
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// otherwise do some other stuff
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}
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void ThreadSafeBlockScope(void) {
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// we're not in the lock here...
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{
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nsAutoLock lock(mLock);
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// but we are now, at least until the block scope closes
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}
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// ...now we're not in the lock anymore
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}
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};
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A similar stack-based locking object is available for PRMonitor. The
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major difference is that the PRMonitor must be created and destroyed
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via the static methods on nsAutoMonitor.
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For example:
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Foo::Foo() {
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mMon = nsAutoMonitor::NewMonitor("FooMonitor");
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}
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nsresult Foo::MyMethod(...) {
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nsAutoMonitor mon(mMon);
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...
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// go ahead and do deeply nested returns...
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return NS_ERROR_FAILURE;
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...
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// or call Wait or Notify...
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mon.Wait();
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...
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// cleanup is automatic
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}
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*/
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#ifndef nsAutoLock_h__
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#define nsAutoLock_h__
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#include "nscore.h"
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#include "prlock.h"
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#include "prlog.h"
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/**
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* nsAutoLockBase
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* This is the base class for the stack-based locking objects.
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* Clients of derived classes need not play with this superclass.
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**/
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class NS_COM nsAutoLockBase {
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protected:
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nsAutoLockBase() {}
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enum nsAutoLockType {eAutoLock, eAutoMonitor, eAutoCMonitor};
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#ifdef DEBUG
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nsAutoLockBase(void* addr, nsAutoLockType type);
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~nsAutoLockBase();
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void Show();
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void Hide();
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void* mAddr;
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nsAutoLockBase* mDown;
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nsAutoLockType mType;
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#else
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nsAutoLockBase(void* addr, nsAutoLockType type) {}
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~nsAutoLockBase() {}
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void Show() {}
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void Hide() {}
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#endif
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};
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/**
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* nsAutoLock
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* Stack-based locking object for PRLock.
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**/
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class NS_COM nsAutoLock : public nsAutoLockBase {
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private:
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PRLock* mLock;
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PRBool mLocked;
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// Not meant to be implemented. This makes it a compiler error to
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// construct or assign an nsAutoLock object incorrectly.
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nsAutoLock(void) {}
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nsAutoLock(nsAutoLock& /*aLock*/) {}
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nsAutoLock& operator =(nsAutoLock& /*aLock*/) {
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return *this;
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}
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// Not meant to be implemented. This makes it a compiler error to
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// attempt to create an nsAutoLock object on the heap.
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static void* operator new(size_t /*size*/) CPP_THROW_NEW {
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return nsnull;
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}
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static void operator delete(void* /*memory*/) {}
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public:
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/**
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* Constructor
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* The constructor aquires the given lock. The destructor
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* releases the lock.
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*
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* @param aLock A valid PRLock* returned from the NSPR's
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* PR_NewLock() function.
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**/
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nsAutoLock(PRLock* aLock)
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: nsAutoLockBase(aLock, eAutoLock),
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mLock(aLock),
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mLocked(PR_TRUE) {
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PR_ASSERT(mLock);
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// This will assert deep in the bowels of NSPR if you attempt
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// to re-enter the lock.
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PR_Lock(mLock);
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}
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~nsAutoLock(void) {
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if (mLocked)
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PR_Unlock(mLock);
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}
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/**
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* lock
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* Client may call this to reaquire the given lock. Take special
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* note that attempting to aquire a locked lock will hang or crash.
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**/
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void lock() {
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Show();
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PR_ASSERT(!mLocked);
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PR_Lock(mLock);
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mLocked = PR_TRUE;
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}
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/**
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* unlock
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* Client may call this to release the given lock. Take special
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* note unlocking an unlocked lock has undefined results.
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**/
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void unlock() {
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PR_ASSERT(mLocked);
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PR_Unlock(mLock);
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mLocked = PR_FALSE;
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Hide();
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}
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};
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#include "prcmon.h"
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#include "nsError.h"
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#include "nsDebug.h"
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class NS_COM nsAutoMonitor : public nsAutoLockBase {
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public:
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/**
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* NewMonitor
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* Allocates a new PRMonitor for use with nsAutoMonitor.
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* @param name A (unique /be?) name which can reference this monitor
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* @returns nsnull if failure
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* A valid PRMonitor* is successful while must be destroyed
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* by nsAutoMonitor::DestroyMonitor()
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**/
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static PRMonitor* NewMonitor(const char* name);
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static void DestroyMonitor(PRMonitor* mon);
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/**
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* Constructor
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* The constructor locks the given monitor. During destruction
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* the monitor will be unlocked.
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*
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* @param mon A valid PRMonitor* returned from
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* nsAutoMonitor::NewMonitor().
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**/
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nsAutoMonitor(PRMonitor* mon)
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: nsAutoLockBase((void*)mon, eAutoMonitor),
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mMonitor(mon), mLockCount(0)
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{
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NS_ASSERTION(mMonitor, "null monitor");
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if (mMonitor) {
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PR_EnterMonitor(mMonitor);
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mLockCount = 1;
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}
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}
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~nsAutoMonitor() {
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NS_ASSERTION(mMonitor, "null monitor");
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if (mMonitor && mLockCount) {
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#ifdef DEBUG
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PRStatus status =
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#endif
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PR_ExitMonitor(mMonitor);
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NS_ASSERTION(status == PR_SUCCESS, "PR_ExitMonitor failed");
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}
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}
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/**
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* Enter
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* Client may call this to reenter the given monitor.
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* @see prmon.h
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**/
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void Enter();
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/**
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* Exit
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* Client may call this to exit the given monitor.
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* @see prmon.h
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**/
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void Exit();
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/**
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* Wait
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* @see prmon.h
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**/
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nsresult Wait(PRIntervalTime interval = PR_INTERVAL_NO_TIMEOUT) {
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return PR_Wait(mMonitor, interval) == PR_SUCCESS
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? NS_OK : NS_ERROR_FAILURE;
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}
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/**
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* Notify
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* @see prmon.h
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**/
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nsresult Notify() {
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return PR_Notify(mMonitor) == PR_SUCCESS
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? NS_OK : NS_ERROR_FAILURE;
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}
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/**
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* NotifyAll
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* @see prmon.h
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**/
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nsresult NotifyAll() {
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return PR_NotifyAll(mMonitor) == PR_SUCCESS
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? NS_OK : NS_ERROR_FAILURE;
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}
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private:
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PRMonitor* mMonitor;
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PRInt32 mLockCount;
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// Not meant to be implemented. This makes it a compiler error to
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// construct or assign an nsAutoLock object incorrectly.
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nsAutoMonitor(void) {}
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nsAutoMonitor(nsAutoMonitor& /*aMon*/) {}
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nsAutoMonitor& operator =(nsAutoMonitor& /*aMon*/) {
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return *this;
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}
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// Not meant to be implemented. This makes it a compiler error to
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// attempt to create an nsAutoLock object on the heap.
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static void* operator new(size_t /*size*/) CPP_THROW_NEW {
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return nsnull;
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}
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static void operator delete(void* /*memory*/) {}
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};
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////////////////////////////////////////////////////////////////////////////////
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// Once again, this time with a cache...
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// (Using this avoids the need to allocate a PRMonitor, which may be useful when
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// a large number of objects of the same class need associated monitors.)
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#include "prcmon.h"
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#include "nsError.h"
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class NS_COM nsAutoCMonitor : public nsAutoLockBase {
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public:
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nsAutoCMonitor(void* lockObject)
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: nsAutoLockBase(lockObject, eAutoCMonitor),
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mLockObject(lockObject), mLockCount(0)
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{
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NS_ASSERTION(lockObject, "null lock object");
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PR_CEnterMonitor(mLockObject);
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mLockCount = 1;
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}
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~nsAutoCMonitor() {
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if (mLockCount) {
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#ifdef DEBUG
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PRStatus status =
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#endif
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PR_CExitMonitor(mLockObject);
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NS_ASSERTION(status == PR_SUCCESS, "PR_CExitMonitor failed");
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}
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}
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void Enter();
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void Exit();
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nsresult Wait(PRIntervalTime interval = PR_INTERVAL_NO_TIMEOUT) {
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return PR_CWait(mLockObject, interval) == PR_SUCCESS
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? NS_OK : NS_ERROR_FAILURE;
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}
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nsresult Notify() {
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return PR_CNotify(mLockObject) == PR_SUCCESS
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? NS_OK : NS_ERROR_FAILURE;
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}
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nsresult NotifyAll() {
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return PR_CNotifyAll(mLockObject) == PR_SUCCESS
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? NS_OK : NS_ERROR_FAILURE;
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}
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private:
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void* mLockObject;
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PRInt32 mLockCount;
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// Not meant to be implemented. This makes it a compiler error to
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// construct or assign an nsAutoLock object incorrectly.
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nsAutoCMonitor(void) {}
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nsAutoCMonitor(nsAutoCMonitor& /*aMon*/) {}
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nsAutoCMonitor& operator =(nsAutoCMonitor& /*aMon*/) {
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return *this;
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}
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// Not meant to be implemented. This makes it a compiler error to
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// attempt to create an nsAutoLock object on the heap.
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static void* operator new(size_t /*size*/) CPP_THROW_NEW {
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return nsnull;
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}
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static void operator delete(void* /*memory*/) {}
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};
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#endif // nsAutoLock_h__
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